1. Technical Field
The following disclosure relates to an image forming apparatus provided with an exposure unit.
2. Prior Art
Conventionally, an image forming apparatus provided with an exposure unit has been known. In such an image forming apparatus, problems as indicated below have been known.
There has been an image forming apparatus having a housing, which is formed with an opening, a cover capable of closing the opening, a holding member provided to the cover and support an exposure unit with a predetermined play. Typically, in such an image forming apparatus, hooks are provided to the holding member, and the exposure unit is hung from the holding member as the hooks engage with a part of the exposure unit.
Each of the hooks has a supporting surface on which the exposure unit is supported, a protrusion which protrudes upwardly is formed, while the exposure unit has a hole in which the protrusion is received. When the cover is opened/closed, that is, when the exposure unit is in a state where it is being supported by the hooks, the exposure unit does not move relative to the holding member as the protrusion engages with the hole.
In known art as described above, when the cover is closed, the exposure unit is supported by a photoconductive drum, thereby the holding member is moved downward with respect to the exposure unit. Then, the protrusion is disengaged from the hole and the exposure unit becomes movable with respect to the holding member in an auxiliary scanning direction. With this structure, when the cover is closed, a unit-side positioning portion formed on the exposure unit is abutted, in the auxiliary scanning direction, against a housing-side positioning portion so that the exposure unit is appropriately positioned with respect to the housing.
In the above-described image forming apparatus, however, when the cover is moving (i.e., being closed/opened), the protrusion is inserted in the hole, which prevents relative movement between the exposure unit and the holding member in the auxiliary scanning direction. Since the exposure unit does not move with respect to the holding member, the unit-side positioning portion and the housing-side positioning portion may interfere with each other when the cover is being moved.
There has also been known an image forming apparatus having an exposure unit as indicated below. The exposure unit has an LED head provided with a plurality of LEDs (light emitting diodes), and an LED holder which supports the LED head via a plate spring. In this conventional art, a casing of the LED head and the LED holder are made of resin, while the plate spring is made of metal.
Since the plate spring is made of metal, it is necessary that a conducting member which grounds (i.e., connects the plate spring to the earth) should be provided to the LED holder. That is, the LED holder should be formed to have a sufficient space in which such a conducting member is arranged. Therefore, the LED holder is upsized and the image forming apparatus is also upsized.